The present invention relates to refiners for wood pulp or the like, and more particularly to improvements in refiners wherein stationary refining members flank rotary refining means in the chamber of the housing whose inlet admits stock for treatment by comminuting projections (e.g., ribs) on the neighboring surfaces of stationary refining members and rotary refining means.
It is already known to utilize in a disc refiner two coaxial or eccentric discs each of which is driven by a discrete prime mover and which have neighboring surfaces provided with ribs or otherwise configurated projections which comminute the material to be treated while the material advances from the inlet toward the outlet of the stock chamber. Such refiners are rather expensive because they must employ several prime movers. Furthermore, the adjustment of one or both discs axially of and relative to each other is complex and time-consuming because the discs must be adjusted with or relative to their prime movers.
It is further known to use a pair of discs one of which is stationary and the other of which rotates relative to the stationary disc. Such refiners are unsatisfactory because their output is relatively low.
It is also known to dispose two rotary discs between two stationary discs so that each rotary disc cooperates with a different stationary disc. The rotary discs are mounted at the opposite sides of a disc-shaped carrier which is driven by a shaft. The stock is fed through one of the stationary discs to enter the space between the one stationary disc and the respective rotary disc, and some of the stock is allowed to pass through relatively small openings in the rotary discs and carrier to enter the space between the other rotary disc and the other stationary disc. Such refiners are not entirely satisfactory because the quantity of stock which passes through the rotary discs and the carrier is relatively small so that the major part of the stock is treated between the one stationary disc and the corresponding rotary disc. This causes excessive wear upon the ribs of the other rotary disc and the other stationary disc as a result of metal-to-metal contact between the respective ribs. Moreover, the assembly of discs inclusive of the carrier is rather long and bulky, and the energy requirements of the prime mover for the rotary discs are high because the prime mover must rotate the rotary discs, the relatively heavy carrier between the rotary discs, and the means for coupling the rotary discs to the carrier.